Most probably your theme doesn’t have <?php wp_footer(); ?> in footer, so please edit the footer of your theme and insert that code.
To edit the theme go to Design >> Theme Editor >> Select “Footer.php” from right hand list >> and paste <?php wp_footer(); ?> just before the ‘< /body >’ tag.
If possible add this code near to WordPress link.
The “disable Content selection” will start working.

WP Copyprotect is bad for the SEO?

No, This plug-in is developed in PHP and javascript, for this reason the plug-in does not affect search engines, it only affects the user’s browser that tries to copy your content. Search engines can read the content of your blog.

Avaliações

The plugin is working greatly except in Firefox browser (version 58.0.2 64-bit). I'm still able to select cursor on text and copy it. In other browsers such as Google Chrome, IE, Opera it works perfectly. Any solutions before I buy the premium version?